The primary components of a drivetrain of a motor vehicle are a drive motor and a transmission. A transmission provides torque speed conversion and thus converts the supply of traction force of the drive motor. The present invention relates to a method for operating a drivetrain comprising at least one drive motor and one automatic transmission. Within the scope of the present invention, the term automatic transmission shall include all gear mechanisms with automatic gearshifting, which are also referred to as automatic multi-ratio transmissions.
From DE 100 35 479 A1, a method is known for operating an automatic transmission, according to which consecutive upshifts or consecutive downshifts can be performed in an overlapped manner to improve the shifting speed. To do so, while each first upshift or downshift is carried out, a shift element that is required for the subsequent second upshift or downshift is prepared during the current first upshift or downshift such that, upon reaching a synchronous point, namely a synchronous rotational speed, of the current first upshift or downshift, the subsequent second upshift or downshift can be performed immediately.
According to DE 100 35 479 A1, single gearshifts are overlapped, which means that each first upshift or downshift that is performed as well as each subsequent second upshift or downshift are single shifts between two gears directly following each other.
The method known from DE 100 35 479 A1 can be used for an automatic transmission with five shift elements, of which two shift elements are engaged for transmitting torque and/or transmitting power in each forward gear and one reverse gear and three shift elements are disengaged. Such an automatic transmission can be used to implement six forward gears. In the development of automatic transmissions, a trend toward an ever-greater number of gears, particularly for the forward gears of an automatic transmission, can be observed. Presently, for example, automatic transmissions with eight forward gears and one reverse gear are under development, where such automatic transmissions have five shift elements and where, for torque transmission and/or power transmission purposes three of these five shift elements are engaged in one forward gear and one reverse gear and the remaining two shift elements are disengaged. The method known from DE 100 35 479 A1 is not suited for such an automatic transmission.
Starting from this art, it is the object of the present invention to create a novel method for operating a drivetrain comprising at least one automatic transmission and one drive motor.